MGCP: Connection Identifiers are hex strings

The MGCP spec in RFC3435 is quite clear: Connection Identifiers are
hexadecimal strings of up to 32 characters. We should not print and
parse them as integers on either client or server.

Change the internal uint32_t representation of connection identifiers
to a string representation in the client and also in the server.

Closes: OS#2649
Change-Id: I0531a1b670d00cec50078423a2868207135b2436
diff --git a/include/osmocom/mgcp/mgcp_msg.h b/include/osmocom/mgcp/mgcp_msg.h
index b7d52bb..7732865 100644
--- a/include/osmocom/mgcp/mgcp_msg.h
+++ b/include/osmocom/mgcp/mgcp_msg.h
@@ -43,7 +43,7 @@
 
 int mgcp_verify_call_id(struct mgcp_endpoint *endp, const char *callid);
 
-int mgcp_verify_ci(struct mgcp_endpoint *endp, const char *ci);
+int mgcp_verify_ci(struct mgcp_endpoint *endp, const char *conn_id);
 
 char *mgcp_strline(char *str, char **saveptr);
 
@@ -54,5 +54,3 @@
 #define for_each_non_empty_line(line, save)\
 	for (line = strtok_r(NULL, "\r\n", &save); line;\
 	     line = strtok_r(NULL, "\r\n", &save))
-
-int mgcp_parse_ci(uint32_t *conn_id, const char *ci);